The major objectives of the grant proposal involves the study of plasma membrane receptors for prolactin and growth hormone. In order to understand the interaction of prolactin and growth hormone with their receptors, purification and characterization of both prolactin and growth hormone receptors will be continued. Antibodies will be raised to receptors. Fluorescein-labeled hormones will be used to examine internalization and processing of receptor hormone complexes. A second major objective is the purification and characterization of non-primate placental lactogens including rat, sheep, cow and goat. Studies on secretion and turnover are underway using radioimmunoassays. Receptors for placental lactogen are being characterized. The identification and significance of novel brain and pituitary growth factors will be explored using tissue culture systems. Studies on B-endorphin and its influence on gonadotropin secretion during maturation will be continued. Finally studies on the role of human prolactin in health and disease will be continued. In particular the mechanisms by which elevated prolactin decreases testosterone secretion in the male will be explored. Secondly the history of prolactin-secreting adenomas will be examined in a series of patients first identified in 1975.